NWR: Angry and sad......... LONG!

so as most of you know now i got my teeth done in October, Well when we went in we set up a payment plan but we had to pay half of it upfront...$1300 so my mom wrote them a check for me. I am paying the rest on a payment plan. So today i get a letter saying it was my final notice and if i didnt pay id be refered to the credit beureau. This was my first notice!! the letter also said my credit card was declined....i never gave them a CC!!! turns out somehow they got my mom to give them her CC#. they told me she gave it to them and said 'if her payment is late charge it to my card' well without me knowing i was supposed to send my payment Dec 1st they went ahead and tried to charge the card. Luckily it got declined. I told me dad and he was pissed.....so we talked to my mom...now mind you my mother has brain damage from a car accident and you can tell something is wrong by talking to her and looking at her ( she only has 1 eye) she said they asked her for the CC # incase the check bounced....WHY WOULD THEY EVEN THINK IT WOULD?? Why would they talk to her while i was asleep from the anestesia???
So my dad yelled at her because if the card wouldnt have declined they would have been out of $$ for food shopping and chirstmas cause my dads pension check doesnt come for another week!!!! I am so pissed at this dentist. why would they even chearge the full ammount when i am supposed to be on a payemnt plan??? they should have only charged $200!!!!!!!!! ug i am so annoyed right now. luckily its worked out and the card wasnt charged but i feel bad for my mom cause she didnt realize she did something wrong and is upset now!.....i am so pissed i just needed to vent
sorry so long!