ESA

Hi my husband is on contribution based esa, support group and was transferred from incapacity benefit to esa some years ago. When he was transferred the letter stated that he would receive a transitional addition as the esa was lower than what he was getting on incapacity benefit. He has continued to receive this addition as the esa is still lower than what he was getting before. He received a letter about the income based esa which i think has gone out to lots of people and although we were sure he was probably not due it as I work 21 hrs a week we sent it off anyway. We then received a letter to say that he was not entitled it as I earned too much. However, he has now had a letter saying that the transitional addition has been removed even though there has been no change of circumstances and he is still in the support group. He rang them up and they have said he is not entitled to it anymore as I earn too much even though he is on contribution based. He argued this with the person on the phone but they insisted that this was correct. Does anyone know if this s right? Thank you