Leicester Tigers boss Richard Cockerill lashed out at the officials following his side's victory over Gloucester at Welford Road.
Cockerill has unhappy in particular with the officiating of the scrum's in his side's 17-12 win, with the Tigers penalised on many occasions.
"I am lost for words. I have spent 30 years in the middle of scrums. I coach it every day," said Cockerill.
"We try to be really professional and then we have to deal with that. It's just not good enough. It has got to end, enough is enough.
"He [Small' needs to look at it and see his faults and try and improve. That's the whole point of coaching, whether you are a referee or a rugby coach.
"Where is the consistency? We have got a massively dominant set piece because we spend money there and coach it and today we did not get the reward we should have.
"Guessing is the word I'd use and it's not good enough. Big games decide championships and European spots. You have to get it right."
"It was a hard-fought game. We led for large parts, which is testimony to how they work hard for each other," said Gloucester director of rugby Nigel Davies.
"If we are honest we were second best at the set piece. It was probably a fair
result although we could have snuck it at the end."