Poor after sales service

I been waiting almost 2 months for Defy to exchange my gas stove. After numerous attempts to fix the appliance the problem was not resolved. They promised to exchange it for me. On 3 March I they called to say they have the new stove but need to come together with a technician to complete the exchange. I followed up with them during the last week if March where they said the technician would be available on Tuesday 23 March. This has still not materialised.