If your mortgage lender has obliged you to open a bank account with them, for the sole purpose of the mortgage payments, and is also charging the account with commissions for maintenance, then this recent ruling from the Audiencia Provincial court in Barcelona might be of interest (reference number for the ruling: AP Barcelona, 128/2019, de 31 de enero, Rec. 1204/2017).
The court ruled that the clause in the mortgage contract, obliging you to open a bank account just for the purpose of the direct debit payments related to the mortgage, is in itself not abusive, but when they charge commissions for maintenance, it is, as they don’t provide any services for the account holder.
The case was a civil one, started by a private indidivual against her mortgage lender/bank. The court ruled that the commissions taken, had to be refunded.