"Our team will guide you through the process " so you do the work and they direct you. It's a scam and you won't get a bank account just pay money for nothing. Do it yourself it's not that hard just collect all the required paperwork first then approach bkk bank
Contact the embassy and explain your circumstance don't waste your time here. See the haters attack you. The embassy will process you quicker when you explain. Sort it before you return to Thailand
You should know the conditions of your visa and it's obligations. You have 14 days before the date and 7 days after or it's a 2000 bht fine. It's not about whether it's useful or not to report to immagration for your 90 days it's a condition of staying in Thailand. Whether you do it or not is up to you and as such you are fined. Don't do it and see what happens