E-car insurance cancellation

Hi ! I have cancelled an insurance policy with e-car and am aware there is a £75 cancellation fee. I have already payed £300 deposit and £180 for 5 months which is £1200. The overall cost of the policy is £1800. They have said they will send a cheque within 14 days if there is any refund due (from my estimates there should be around £400 owed back to me as I have payed £1200 so far and that is only for 5 months of cover). Anyway they have the bank details for an account I dont use anymore I am wondering should I put £75 in there incase they try and take the fee? or will it just be deducted from the cheque with the refunded money they are going to send me?

I cant really contact them direct as it costs £1 a minute to phone them ! and they rarely get back to emails. Hope that makes sence though