Hey,
Same cut-out issue with the Crossfire after only 2 weeks, and the battery would only charge to 76%. I got straight back onto the Halfords branch where I bought it (I am in Dublin) and they took the bike back and gave me their demo model for the interim, which was decent of them (this too has cut a few times). I now know they cant fix this issue, as I am sure they do!
Asked for a price on the Crossfuse and they came back offering a meager discount (expecting me to pay +500 Eur to upgrade) with no accessories to sweeten the deal. I declined and they are now giving me a new Crossfire, they were pushing for a refund (sure they've a pain in their neck at this stage!) even acknowledging "...in case there are more problems down the road" - had to laugh at that.
The staff have been good to deal with (not great; I had to chase constantly,they mislaid the repair docket twice and never checked the battery issue) so I felt some recompense was in order. Either way they'll replace the bike anew and if I get the same issue we'll do this dance again!
These issues aside, the Crossfire is an excellent, especially as a first ebike, and is priced much lower than most others at entry level (about €2k). If I could afford it I'd take the refund and get a Cube, Orbea or Giant....if only!