Home Energy Services

I have a tenant in a bungalow and the boiler is covered by HES contract. Tenant contacted HES in March for annual service booked for 19 April 17. On the 18th she contacyed HES to advise she would not be there on the 19th and to reschedule service, only to be told that HES were not coming anyway as contract had been cancelled. I contacted HES and they said that it was their mistake as the account was being migrated to Homeserve( news to me). I asked them to sdort it out and phone me the next day to confirm, needless to say no phonecall, in the meantime my tenant phones me to say that she has received a phonecall to say HES are at her house to service boiler!. I re contacted HES to find out what was happening and ythey said it would be soreted that day (21st) I asked them to guarantee that they would phone the tenant to rearrange service, guess what they didnt. Ive just contacted HES today 22nd ( sat) andbeen told its an accountancy error and my policy is cancelled!!! Absolurte chaos.