"Offers not applicable to nhs patients"

Myself and my wife visited the St. Helens store. We were seen promptly even though we called in without an appointment. Af ear the eye test we were both recommended to have distance and reading glasses. My wife had already chosen her glasses by the time I had joined and she commented that we could get two pars of glasses if we chose above 70 pounds, we were using the nhs voucher so we would only need to put a small amount to it. We were suddenly told that the offer for two for one was only for their private paying customers not those with an nhs voucher,. We felt like second class citizens and were quite humiliated so we chose quickly and left. We were fitted with the glasses a week later and they are ok. I left feedback on the spec savers website to say how unhappy we are at being second class because we don't have the money to pay in full. I was contacted by the store manager by email and I gave home a ring because they said there had been an error. They told me that the two for one did only apply to those fortunate enough to be able to pay in full but there was an offer where by we could deduct the thirty eight pounds or so that the nhs provides on the voucher and that we could have taken that amount off the cost of the glasses, in our case 99 pounds and then get two pairs, they also offered to go halves on the cost. Good though this was I will not be taking home up on the offer, I would prefer in future to visit an optician who will not be treating me as "an nhs customer" but as a valued customer who just cannot afford to pay the full cost.