Is there a chance they will come back for the rest of the money?
What would happen if I closed the account?
If you agreed to buy something for £500 then that is what you owe. You should bank the remainder of the money against the time they come asking for it. If they don't claim it within so many years (it depends on your local statute of limitations) the money is yours.
If you had purchased something for £5 but been charged £500 what would you be doing? - closing the account, trying to hide, keeping your mouth shut and the rest ? eh?
Of course if you are not honest enough to point the mistake out to them then they will find it themselves at some later point and come after you for the balance.
They will be quite justified in doing so.
The only person who will come off badly will be yourself for having not contacted them promptly in the first instance, quickly followed by changing your bank account and trying to disappear from their radar.They will find you, you will end up paying the balance and probably - if they have to take you to court - a lot more than it is at present with all the costs they will also be awarded.
If you were to do the proper thing now you never know they may give you a discount as a thank you - you will keep your honour intact and the Karma of the world will have one less injury / one more healing.
unlikely they will track you down via yahoo answers
just don't say anything or mention it ..... maybe make sure you keep the money in reserve for a about 2 months ... they may come back for it ... ( anything longer than , that i would say your in the clear )
however , if they come back later ...you can probably get off with paying in instalments ....
just keep quiet ....
similar things have happened to be in the past .... i bought a washing machine from argos ... they called me and gave me a delivery date of 4 weeks .......when they rang to confirm , i said it was not good enough and after haggling they got it to me 1 week ..... it arrived in one week and another arrived 1 month later ...
i also ordered £400 worth of shopping from tesco's some 8 years ago ( maybe more ) .... and it turned up , with double of everything .... we used to have 10 toilets in my old house , so ordered 10 packs of toilets rolls , 20 @ 18 per pack turned up ...... i had 360 toilet rolls
good job there was women in the house or i would still be using that batch to this day ( women , main destroyers of rainforests and cause of global warming )
I would guess that they will come back for the remaining £495 which you owe. Closing the account will solve nothing, it is you that owes the money not your bank. I imagine that they will sue you for the money if you don't pay up, especially now that you have high-lighted it on here! (Travel company staff also use Answers you know).