whats the point of having a contract with you

Where to start with you people. Why is it so hard to stick to a contract which clients have signed with you? do you loose the contract and charge clients what ever you want? I signed a contract for 600 a month and each month you guys deduct from 650 to 698. After going into a store to get this sorted it lasted a month and guess what.... back to the same bull**** of taking more money that is needed. i have sent emails and called in and yet nothing has been done about this matter. yes all the calls that " have been record" cant be found and no notes on the system added either...

I have requested a proper invoice from you guys to prove the valid amount being taking from me every month and yet nothing has been sent to me.... and in my eyes thats called theft and breach of the contract.

This matter needs to be sorted out. I just want to know how many people have you been doing this to and for how long.