Appalling service

Appalling service delivery from the start. Constantly messing me around with times, calling 30mins before to tell me they wont make it only to reschedule and have it happen again! Oooor tell you they cant make it when YOU call as they are late. Also what they quote is never what they charge, they gave me a service cost only to only add VAT when billing me! We have a noise issue in the actual unit in the house, it was discussed when they serviced it after 6 months and then technicians came again to assess it as well as me sending a recording of the noise. A part was replaced they said may be the issue and if not, a new unit will be installed as it's still under warranty (oh all while again messing me around with times). The noise is persisting along with 2 other not normal sounds, so time to honour the replacement. We set a time for monday, only to be told they wont make it, so reschedule for today...only to be told they wont make it, now "coming Wednesday 8:30" - it's now almost 9am - but for another assessment....of the same noise!!!! We want the replacement as we were told!! Your service levels are nothing to what you say on your website!