Really? Doubt I would use that as a criteria to judge ones reputation.
I can name tons of breeders starting their snakes on mice hoppers and continuing feeding mice....that includes big names in this industry. Keep in mind that you can breed a whole lot of more mice than rats with the same real estate therefore breeding for a large collection makes a lot of sense.
Now to the OP
There are a lot of things that could be going on and before jumping to conclusion and assist fed here are the things I would do if not attempted already.
1# Provide a 6 quarts tub (no larger) with aspen bedding and a small plastic flower pot saucer as an hide with a hot spot of 86/88.
2# No more handling
3# Feeding in the tub a week after the last changed were made and offer a LIVE prey no more than every 7 days.
4# If it fails I would try the brown paper bag trick.
5# If it fails again I would offer a rat crawler just in case.
Before assist feeding all options must be exhausted, there is no time frame to assist feed it's a matter of monitoring your animal not only it's weight but overall look as well.