Did someone use credit card to give you an upgrade?
That happened to me on here, the guy sold some upgrades and used his credit card, then got banned, then a few days later he disputed the payment and now I'm in negative credits.
Your credit card company denied the payment, or charged-back on JaGeX, your going to have to go buy a UGC card to balance the negative credit, they won't accept any more credit cards from you.
you can buy membership under Pay By cash way.
jagex take this payment as well, there is no way of charge back for pay by cash.
you can order pay by cash through me.
ps: this would be a bit higher then normal way.