Cheers for the further info.
It's a shame I didn't come across EGO gear earlier, we bought good quality stuff previously over the last few years (Stihl) hedge trimmer pressure washer so expected other Stihl items to be of good quality and solid build, but the strimmer we bought just isn't up to snuff and broke/failed within the first month.
Dealer says it could just be a one-off but the US Stihl website says otherwise IE weak gear to motor link etc which is a shame, so after this disappointing episode I don't expect to be buying any new gear apart from another strimmer for at least 5 years now.. well I hope not, so not much point in spending extra cash on the bigger charger/battery, but it's good advice for those that follow not to fall into the same battery gear trap, or at least give food for thought anyway.
I'll keep you posted on further events.