Barclaycard Payment Minor Issue

JDC14

Just been paid, so go to pay off the full amount outstanding on my Barclaycard (I pay it off in full every month).

A payment wasn't due (according to Barclaycard as it assumed a refund from gambling winnings as a payment) - but as I went to pay off the remaining balance, £7.10 was stated as pending, but was included in the balance.

I went to make payment for the full amount - but it just went "Ooops you can't put an account into credit" and suggested an amount approximately £80 less was enough to clear the statement.

I haven't got any payments pending to BC, so can anyone explain this?

JDC14

£83 is still showing on the balance - just tried to pay it off and it said "oops cannot put account into credit" again - but suggested I paid £304 to clear the last statement (A payment they had already accepted).

Any ideas?