Dell payment cock up

A week and about 15 emails later we're still waiting for Dell to send details of how we can pay securely by credit card. For the first 14 replies they kept sending the same details for paying by cheque, but we want the security of paying by credit card, which was the method offered when we initially ordered/paid for the machine.

They've finally sent an invoice number, but no details of the discount they're offering, and no option to pay securely - they're expecting us to enter all our credit card details into a standard email.

Thinking about it the discount is meaningless anyway as we probably originally had a Quidco or voucher code discount set up.

We've had an offer from the credit company to phone them our card details so we're getting Dell to confirm this will be accepted, as Dell themselves seem completely incapable of accepting an online credit card payment.