Hai,
There is only one solution for this, try to stop the bid options for any items. Hence, Only put the fixed price for the item you are listing. If the item was likely to be any requirement for the buyer , then they will purchase it immediately if they want, In my opinion, bid option is waste of money to sellers and there is no useful of it. I have also faced the same problem on 3 months ago. Now I am selling the items in fixed price only. Try to sell the items in fixed price in my opinion. That's it. If my answer not given any message to you means please ignore.
Thanks & Regards,
Raghavendra.nss