I've been with Specsavers for over 15 years and with 4 different branches. Always fine - cheap but do the job.
My Dad had an horrendous experience with, and yes I'll name them as they were that awful, Dolland and Aitchison in Chester, earlier this year. He had an appointment and told a young girl on the front desk that he had arrived, 5 mins early. Staff then ignored him for 45 mins. He asked the girl what was happening, and she shrugged. Was overheard by an older member of staff, who told him that his optician hadn't turned up for work that morning, but to sit tight as they were waiting for a locum to come over from Manchester. So my Dad (aged 68 and with wonky legs, BTW) sat back down and waited for another 30 mins. After which he asked what was happening, only to be met with another shrug. So he left.
Being a grumpy old complainer I wrote a complaint letter for him. D&A just sent back a one-liner - "sorry you have had a bad experience in our store, we value your custom and look forward to seeing you again soon". My Dad's one line response involved the words "shove", "service", "your", "backsides", "your" and "up".
After an earlier visit to D&A he came home looking worried and told us how suprised he was at the cost of glasses nowadays. He told us he'd been charged over £800. It turned out that the D&A staff had seen him coming, what with him being a little on the doddery side, and had only shown him designer frames. He'd bought a pair of Dolce & Gabbana frames with Reactalite lenses, neither of which he needed. We tried to persuade him to cancel the order and go elsewhere, but he was too embarrassed to admit he'd made a mistake and went ahead with it.
So, as you can guess, I'd avoid D&A at all costs!