Orgent- Thalys reservation problem

To Rick Steves' Travel Dept.: When we purchased our Eurail passes several weeks ago (which I didn't realize you sold at the time), I e-mailed Eurail about how to buy first class Thalys passes for a one way trip from Psris to Amsterdam. I was told I had to deal with Thalys directly. I first e-mailed their customer service department, but was told that they did not make reservations and that I had to phone their reservation office in Europe. I phoned their, made a semi-flex reservation for a decent fare, but then found out my Visa Sapphire card payment would not go through. I called back several times after (before and after the recent strike), and eventually found out from the representative I spoke with today that they are no longer accepting any foreign credit card payments because they lost 3 million euros in 1 month due to bad credit cards recently (and have since refused to accept foreign credit cards). At this point, I feel like panicking because both full fare first class and Pass 2 fares have gone up a lot and there are no other trains that travel from Paris to Amsterdam. The representative I spoke with recommended that my son make a reservation and pay with cash when he goes to Paris in late June to study, but I would prefer not putting the burden on him (and am also concerned that fares will be even higher then). What should I do? Thank you for your prompt assistance.