Bots entering bids?

[turkey1138]

In the last two days I’ve had around 15 bids cancelled/retracted on the same item.  All the bids are done by users who have weird names with zero feedback.  I feel like it’s being done to keep the price lower.  Is there anything I can do?  Thanks!

[disneyshopper]

In the future you can list as fixed price, no offers, Immediate Payment Required, and the listing will stay up until it is actually paid for.