Had annual service in Nov.2019, no issues. Two weeks later, issues with some radiators not heating properly despite bleeding them. Engineer called yesterday to check radiators etc.. and informed me the system needs balancing, draining down each radiator individually to check the system. Emailed this info. to the office today. At about 4pm. loud noises and knocking sounds coming from the boiler, immediately switced it off and attempted to call the office on both phone. nos. using to phones.Waited, waited and waited, 40 minutes on hold,of course no reply. This company must be one of theworst for so called customer services. In the end emailed with the issue and am awaiting reply. Having paid two payments of £80 a time prior to the jobs being undertaken somehow feel taken for a ride. Will wait and see the outcome.