I'm really pleased that you've got your battery issue sorted. Mine was nearing the end of the warranty period and had already been replaced once in that time. There was certainly a reluctance to offer a replacement as I didn't have the original paper receipt from 2014. It probably wouldn't have been readable as the thermal paper-type receipt had lightened considerably over time.

It does annoy me that even with proof from an independent auto electrics specialist that the battery was shot, Halfords claimed that their testing (with a Yuasa-branded tester) showed that there wasn't any problem. I left my dud silver Yuasa battery with the local Halfords branch and asked the manager to call me to discuss replacement. No phone call received.

Yuasa Black
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Not sure if anyone else saw those 'Yuasa Black' batteries being offered with a lifetime warranty but these disappeared from their stores/websites pretty sharp-ish with no explanation. I tried to buy one in the middle of last year. Something fishy going on there, methinks.
Original non-working link for Yuasa Black battery: http://www.halfords.com/motoring/bul...2v-car-battery
I've also attached a screenshot of the email confirming the order but turned up to discover that there was no battery and no-one knew or claimed to know anything about this fabled lifetime-warranty battery for £180.

My A8L is currently very happy running on silver Bosch juice.