Volkswagen Polo 1.0 1998 oil pressure light?

Hi ive got a 1998 volkswagen polo with only 73000 miles on the clock but im having problems with the oil pressure.

The oil pressure warning light came on a few weeks ago and I took it to a garage and they checked the switches and replaced the oil pump and it worked fine for a couple of days but then the oil pressure warning light came back on.

Since then i havent driven it but everytime i start the car the oil pressure warning light comes on.

I dont know what else could be the causing it. As i said it worked fine for a couple of days after replacing the oil pump but then the problem started up again. To strip the engine the garage wants £500 and that doesnt include any work it may need. I dont know if this is worthwhile or if i should just cut my loses. The cars in excellent condition and has been serviced every 10000 miles so its been kept well but i dont want to spend more money and still have the problems

Any help and advice on what you recommend me to do would be appreciated as i dont know much about cars.

Thanks