What issues can arise with the Thai eVisa website payment process and how can they be resolved?

I’ve never known a Thai visa website that worked flawlessly. They’re almost always crap and Thais don’t care much either for maintaining things to prevent breakdown nor do they care much for fixing things when broken. That means you generally end up with a shoddy user experience. My advice would be to cancel it and start over using a different browser and keep tying till you get there. Fake it till you make it! For what it’s worth, it took me three days, four devices and as many browsers to get through the processs for a new Thai visa using their embassy in London. Got it eventually though! Good luck.