Yes, you can restrict it by defining an upper limit at the terminal or merchant level. Institutions generally do not want to lose turnover, but turnover restrictions can be applied when there is a suspicious merchant or when the agreed working terms fall below cost.
In addition, a per-transaction amount limit can be set in the terminal or merchant field. For example, you can define limits such as 9,999.99 TL or 99,999.99 TL for a single transaction on a terminal. (These amounts can be increased based on the number of characters.) You can also set amount-based limits, such as allowing transactions of at most 50,000 TL each.
If the reason for defining an upper turnover limit is the working terms, it would be healthier to add a second rate field for the turnover overage limit and to calculate the portion exceeding the limit at a different rate; this way, no turnover will be lost.
Depending on your developments, you can break turnover restrictions down by terminal, merchant and customer.
My recommendation is to keep the limits flexible and not lose your turnover unless you have a suspicion about the merchant or are making a loss on the rate.