Repeatedly wrong invoices, not offset by deductions

Hi, I was on a call w BDC yesterday twice because i got an invoice for which the amount was not offset by deductions they actually made.

In short, BDC owes me 2 cents after offsetting the invoice w deductions already made.

Instead the invoice is marked as unpaid, and shows that i owe than 1000+ euros. I'm pretty sure it was displayed correctly for a moment last night, but it's back to me owing them this. I would normally just dispose, but they have mentioned that the amount could be taken from my bank account directly (i gave authorization for this).

What is happening? Is this a common issue on their end? Wrote already but seems like it takes a while to hear back and they're lost (my call w their agents yesterday was a mess, they seemed to have no clue).

Thanks for your suggestions on advance.

Vincent