The next step may be to write to PALS -
https://www.nhs.uk/Service-Search/Patient-advice-and-liaison-services-(PALS)/LocationSearch/363.
Possibly write to the practice manager (don't need a name, just the title) copied to PALS.
If they get something in writing they have to make a formal response.
Further avenues are the CCG and Health Watch.
The main point is they can brush anything face to face or on the phone under the carpet, but a written complaint triggers procedures.
As far as I know this is one thing that will be visible to the CQC when they asses the practice, so a written complaint is taken far more seriously because there is a paper trail.
Not a step to be taken lightly, but if they are doing this to loads of people then a written record can focus the mind because they can't do the "never happened before" routine.
For the OP this looks to be a shambolic merger between two practices. This may explain it, but it doesn't justify or excuse it.