Promised to get back to me

I bought a trimtech petrol lawnmower from builders warehouse15/11/2014 and took it back for repairs on the 14/02/2015 (sucking oil into the airfilter) job no 20347. I used it twice and had to take it back for the exact same problem. Job no 29821 I asked to speak to the manager and was promised it would be sorted out and he would get back to me on the 6/04/2015. I have still yet to hear from him or builders warehouse and on phoning them today suddenly no one knows who the manager is and all that happened is i was transferred from person to person without getting any help.