A credit booking remains unclear despite enquiry. You want a comprehensible response and, if necessary, a correction. For an effective complaint a narrowly defined factual situation helps more than an extensive collection of general accusations. This Austrian article does not give a legal assessment of the booking.
Name the concrete result
First write down what you want clarified: for example the calculation basis of a specific item, its contractual allocation or the correction of a verifiable booking error. Amount, booking date and affected credit must be clearly attributable. Use the company’s appropriate confirmed channel of communication when corresponding with the bank.
The FMA recommends first going through the complaints process of the company concerned. It names the company’s complaint management or ombuds service as typical points of contact. [FMA-BESCHWERDE] An earlier non-binding telephone conversation is therefore clearly distinguished from a documented complaint.
Build a small chain of evidence
In the completely fictional case an additional charge of 240 euro is disputed. The person concerned provides the specific account statement line, the contractual provision they consider relevant and the previous written enquiry with date. They describe which explanation is missing. A private annual statement without reference to the booking would unnecessarily complicate the review.
Attach only documents that are necessary for allocation and explanation. Mark your own assumptions as such. From an unexplained item a proven unlawful deduction does not arise merely through the wording of the complaint.
Pay attention to the response and the actual subject matter
Keep proof of receipt and the response. Check whether the response really concerns the same booking and explains the calculation step you identified. If a specific gap remains, name it in a short follow-up question, instead of re-sending the original entire text unchanged.
The FMA describes requirements for a comprehensible complaints procedure, including understandable communication and justification of a final answer that does not fully uphold the complaint. [FMA-BESCHWERDE] The article deliberately does not specify any made-up general time limit for this.
Choose the appropriate next step
For an FMA complaint the supervisory authority requires proof that you have contacted the company’s complaint management. A written company response is added if it has been received by you within a reasonable period. The condition does not require unlimited waiting for a missing answer. Its task is supervisory review; it cannot enforce an individual solution. For individual dispute resolution it refers to other bodies and courts. [FMA-BESCHWERDE]
Which counselling or mediation is suitable for your case and whether deadlines must be observed needs to be clarified specifically. The achieved stage of work is a verifiable booking question with a complete history of responses. It is not yet proof of a claim and not a promise of reimbursement.