One of my air conditioning units blew a condenser ...

One of my air conditioning units blew a condenser and it stoped working, the technician replaced it for 394.00 when the part only cost 27.00 dollars, and then he said I needed to replace the whole system because of the age of the units, and than was told he would refund the cost of the part if I replace the unit, total BS, I would question there sales tactics, not a transparent company.