Payment is either broken or a scam. Unsure. It gives what looks like a stripe error. Payment processor is on a Somalian domain and the contact page links to a Nigerian twitter account. Payment company claims to be Belgian. Both this site and the payment site domains have private whois info. Very suspect.
I'm sorry for the experience you had. I use tally forms and stripe for payments which are both reputable. I'll see if I can fix any problems with payment. Yes I'm Nigerian and I didn't try to hide that.