Please help for a chargeback case

[qs2]

We are travel agency, here is what happened this year:

Sept. 10 we got request from customer(Let's call him Phillip) for a tour. We communicated with him, send him Itinerary, costs(usd 900), price including and exclusive. He traveled alone. Everything via email.

Sept. 13 Phillip said: i agree with your offer, i would like to book...we offered him 2 kinds of payments: paypal and bank transfer. He choosed paypal.

Sept. 16 he tried to pay. The point is what happened when he paid: at first he used his own paypal account(let's say phillipxxxx#yahoo.com) to pay, but he got problem with own account, he said his paypal card is not current. The paypal account is also not letting him update his card info. So he asked his wife(Let's call her Grace) to pay for him.

In our account we can see the status of the payment from Phillip's account was: first pending, then denied. paypal said the reason is eCheck payment failed.

Sept. 17 we received payment from Grace's account(usd 900). She paid with credit card via paypal. On Sept. 17 we can see payment status of the payment from Grace was completed. So we arranged the tour for Phillip: hotel, car, driver, meals tickets, etc

Sept. 30 to oct. 2, Phillipe traveled with us, after tour we even asked him about the feedback of this tour, feedback was positive.

Oct. 5 we got email from Grace: She claimed both their credit card and checking account have been billed for this tour! She asked us if both payments were received or if only one payment was received.

Oct. 6 we replied, we only got one payment. We DID NOT get any payment from account of Phillip, we only got 1 payment (usd 900) from the account of Grace.

Oct. 14 we got email from Phillip: He claimed both their credit card AND my checking account have been billed for this tour, Please inform if both payments were received or if only one payment was received(actually it was a copy from Grace's email on oct. 5). Our reply was like last time: we only got ONE payment(usd 900) from Grace account, all the money we received is only usd 900.

oct. 25 Grace open dispute and ask her credit card issuer to reverse the charge (called a chargeback). Paypal send me this message: The buyer said it did not pay for the deal through its PayPal account, but instead used other payment methods(Payment by other means)...following is the dispute detail...If you have any other information that can help us resolve this incident, please submit the information through the Mediation Center by November 3, 2019.

Oct. 26 we responsed with whole things with texts and screenshots from email and payments in our paypal account, all we want to prove is that we only got one payment(USD 900) from Grace's account, we dind't got any money from Phillip's account, all the money we got is only usd 900. 

Nov. 11 There is an update on your PayPal Case PP-D-xxxxx, ....the card issuer has decided the chargeback in the buyer's favor.....So we lost $ 900! we even have to pay for the Chargeback fee(about usd 10)!

We have been contacting paypal and buyer for more than 1 month. Paypal said it's decision of grace's credit card Company, this case was closed. Paypal suggested we contact buyer directly, but buyer responded negatively and refuse to pay again...Now buyer don't response for our phone call/sms/email.

My questions are:

1. how can we get our money back? Any information and suggestion is welcome.

2. can i ask paypal send me status of two payments, which should including both transition ids of buyer and seller.(I just found that the transition id of buyer and seller are different! That sucks!)

* The names in this case are just for the convenience of expression and presentation, the amount of usd 900 is very close to the real amount of my lost.

* We just used paypal for 3 years, it's our first chargeback experience, so any suggestion is welcome.

* Our tours normally costs usd 1000 to usd 3000 per person...Now we are very scared to use paypal to collect money