Over billed

I was over billed when I upgraded my account form a 2mg to a 4mg package. (I was charged for 2 modems and a LIT box, of which 1 modem and LIT box was part of the package. I have no idea where the 2nd modem charge came from) After I phoned them and logged a case I was sent an sms on the 1st of December they informed me that it would take maximum 10 working days. I called back on the 15th to find out what was going on and when they where going to refund me. they said that they where going to 'Escalate the matter' and resend me an sms with a new log code. I have phoned hem every day since the 15th and still have no new information on the situation. And no idea when I will get my money back. Never use debit order as you will never see your money when they over charge you. Take the time to do a monthly EFT it will save you in the long run.