They allowed the tenant to not pay for 3 months of a 12 month tenancy. When we informed them, the first time we realised, they were grossly patronising to us. When we showed them our bank statements, still no answer. Only through hassling the tenant consistently did they pay up (i.e. the estate agent had little to do with it).
You have few rights as a landlord when this happens without resorting to expensive court battles. So avoid these people, they do not have the responsibility to be agents.