Complete rip-off !!! Random high prices on glasses !!

I have purchased two pairs of high-power glasses last year. When I visited them again this month, the charge me almost double the price of the glasses( just to replace the glasses in the same frame). For the same quality of glasses, they want €449( base price for glass excluding the frame) + additional charges for labor costs to fix the glass. Its approx €100 more for each side glass compared to what I purchased last year. They just randomly deal with their regular customers and quote random prices, despite being a regular customer. Not at all trustworthy !! They just decide the prices randomly!!

Now, when i ordered the same quality of glasses from another Becker+flöge shop,the price is almost half of €449. It costed me 229€ including the all additional costs. But in general, there are lot of hidden costs. When the health insurance(AOK) is paying some amount for my glasses, why do we have to bear extra costs (5-10€) and why do we have to pay additional charges to fix the glasses in the frame(€20 approx) ???
There are hell lot of hidden costs.

Nevertheless, different shops of becker+fölge quote random prices.