Just a bit of advice about banks and dealing with matters such as these.
I work for a company that makes quite a few charges that were "unauthorized " (it's a very evil company.) so I get to deal with banks quite often. Here are some things i've come across.
1) Even if you tell the bank to stop accepting charges to your account from company X, 9 times out of 10 they will accept further charges.
2) If the account is left open at all...the charges will go through (often overdrawing accounts, see point 1). So leaving the 100 dollars in the account instead of closing it was not a good move. (But from your point of view I understand why you would do that...) ALWAYS close the account if you want to escape further charges
3) With credit cards/ debit cards...changing the number (buy keeping the same account) will not always stop someone from charging you. I've spoken to people who have been charged by us , changed their card numbers and were still charged again. The card issuers assumed that our charges were authorized and simply sent the charges to the new card. Lovely. I know. So, again, close the account and start a new one.
4) get names. and extension numbers (or Id numbers). the better your records are the more credible you seem. I get calls like this every day, if a customer cant prove to me with a name AND extension that they spoke to someone i assume they're lying.
5) be polite and personable, but firm when dealing with people. Think of it from the point of view of your typical paypal cs rep. They get calls like this every day. Make yourself stand out in a positive way. These are real people, they realize your upset , but showing that you can still be professional and polite goes a long way. Usually cs reps are limited in how much they can credit / etc , so most likely you're asking this person to go to bat for you with their supervisors. I, personally, won't do this unless someone is nice to me. If you call and try to bully / scream your way into a credit, it isn't going to happen. If someone is nice , explains things in a calm manner then I have no issue with going and requesting a full credit. Keep in mind that usually these people are trained to say no to credits...so they'll probably have some sort of script to follow about this. if they say no..explain the situation again and ASK (don't command) if they could perhaps request a credit for them from a supervisor because of your circumstances. If they say no again then calmly ask to speak to a supervisor. Repeat the process again.
Remember , you want these people to help you , dont piss them off.
Don't threaten to get a lawyer. Use all over avenues before taking this one. I know it seems like a good card to play , but it's not going to help you out. I've gotten calls where people said they would sue the company I work for over 9.99. If i ever hear someone say they'll sue, I assume they're bluffing. Besides..how many threats of lawsuits do you think these people hear everyday....probably quite a few.
Use it as a last resort...if you speak to a manager and they still wont help you out , calmly explain that since it's quite a large amount of money that you will be seeking legal counsel to resolve the matter. Get all of the information about the company (address, fax number, etc ...because you'll probably need this)
Wow...this was something of a rant...but I deal with this alll day long...so I have strong feelings
Good luck though, you're in the right , I'm sure you'll manage to get your money back.