Jet Airways India review: unauthorised taking of excess payment

I booked my return families flight to bangkok with jet airways . My wife and daughter travelling first, I travel at a later date then we all return on the same date together.
When my tickets where emailed to me I saw that my wife and daughters return flights had been booked for the wrong month - 1 month later .
I phoned jet airways to rectify the matter and change the flights to our original choice.
I had to pay an extra £641.00 that I agreed to but when I looked at my bank account jet airways had taken £961.50 !
When i phoned them them back they admitted this was a mistake but said they could not refund my money, I had to send an email to another office,
I asked for confirmation of our conversation and their mistake - they said no ! I have emailed the office and explained how urgent it is that I have my money( that they should not have )back immediately but have had no reply