Wells Fargo Credit Card Complaint

Wells Fargo Credit card department,

Payoff process Connecticut

I have a credit card with Wells Fargo. At this time, I have three different promotional balance 's on my account. ( They offered special finance of 0 %, for 15 months - Because they claim to apply extra payments to higher interest amounts -, I mistakenly assumed they would add my extra payments to the promotional balance ending soonest. Having checked my last few statements, I see that is not the case. The majority of the money is being applied to the balances with the furthest out end date. When I contacted Wells Fargo, to inquire as to how I might stop this, so my extra payments will be used as intended, I was told that was not possible. I was told they had no way of applying the excess money to any one balance. When I pointed out that that is what they were doing, only in their favor, not mine, I just kept being told he knew how frustrating that must be! When I asked yet again, how I could have the extra money applied to those balances expiring first, he just kept telling me it was not possible. At this time, I have no interest charging amounts on this account, only these - special finance balances, which are accruing no interest. I assume that is how they can get around applying the extra money to those amounts expiring the furthest out, but it still does n't seem right, because this will cause me to have to pay interest on these amounts, as they expire. If the extra money was being applied to those expiring first, each amount would be paid off before it expired, which was my intention. I would like to know if this is legal, and if so, why?