This fee was not part of our conversation/discussion or the estimates that was provided to me while we are going through the closing process.

Every conversation contains a precious nugget.

It is HIGHLY frowned upon in small business purchases, not sure about real estate but I think you should have a conversation with the lender first. 

Document EVERYTHING... every conversation, every contact, every document from the remediation company etc etc etc.Then I would send him a certified letter that states all necessary precautions, accommodations and solutions were done.

I am currently using FUB/Ylopo and zBuyer, working with a few Ylopo social/PPC leads right now but they are going to take Alot of work to convert, zBuyer for SoCal are 99% seniors that are just curious about their home value, so while there's been conversions they are far and few between. 

I had a great conversation with one of the sales reps and yes it is a $5,000 price tag.

Always remember, you do NOT have to stay in a conversation that is going nowhere or is making you feel stressed.

My wife send him our estimate based on our conversations, that was $84,000, but he signed anything or agreed with that estimate.

I had a conversation once with a very smart Dr. who stated that this concept does not exist in all cultures and was/is more prevalent in certain cultures in centuries past.

In the short time I've been actively investing in RE, I've already had to switch my CPA because our conversations usually felt like I was having to tell him how to maximize my deductions.