I think you will find that the OPC prices have risen across the board for a simple reason. That reason is, they disbanded their fixed price servicing at the end of 2019. Those fixed prices were a no-brainer compared to the cost of indy specialists. Around here in south Cheshire with a lot of high net worth individuals, the indy prices were marginally cheaper (around £80 or so) and some were actually dearer than the OPC. Not surprisingly, I used OPC (Chester) for the past 8 years). They quoted me a new fixed price as a regular customer, but that was still considerably more expensive than the prior fixed price scheme. Not all OPC's participated in the fixed price servicing, it was optional for them. Now the indy specialists are less expensive than OPC in this area - though tremendous variation if you shop around - travel to Lancashire such as Westhoughton near Bolton and the prices are considerably cheaper than any indy with a Cheshire or Merseyside post code. Travel to Yorkshire and prices are lower but started to climb when they cottoned on that the OPC fixed price servicing was no more.
I think OPC have shot themselves in the foot with this new positioning. If you are a loyal customer, they will offer you a discounted price akin to the fixed prices before, but still dearer than those fixed prices.
Each has to decide their option and follow their wallet I guess....