REO listing agents pushing their own mortgage brokers’ on my buyers?

Fortunately (or not) there are very few REO listings in Palos Verdes Peninsula area. Of course if one comes along it creates an ugly bidding war that discourages most of my buyers.  I’ve just submitted an offer from one of them to the latest foreclosure.  My client submitted pre-approval letter from her own loan officer she’s been dealing for many years with.  Next thing we know is that listing agent requests everybody who put a bid to get prequalified with lender of his choice otherwise offer is not going to be submitted.  My client called that source and instead of being screened and pre-qualified was aggressively solicited on purchasing loan from that referred lender or else….  She is furious about such practice.  In her opinion she might have disadvantage in presenting and acceptance of her offer if she continues working with her own lender.  Even though it’s all about the price at t he end, she feels she’s being tricked into something unfair.