I am having the same issue. Infinity installed on 14th February. Claimed the next day online, never actually received confirmation so I called BT who put in the claim again, had initial email saying they would let me know if I am eligible, never received it but did receive confirmation I was entitled to is through the contact form
That was 34 days ago and still received nothing, no confirmation, no email from the matercard provider stating its on its way.
Now I am seeking legal advice as I also went with BT due to the decent offer.
Since having BT installed our broadband buffers all the time, WIFI is shockingly bad simple webpages wont even load up despite doing all the suggestions people threw at me.