W203 "C" Class 220 CDI Advantgarde UK

Hi have any of you experienced week rear or broken springs on this or
other low mileage Mercs and particularly in the UK?

I have just had my second rear spring renewed on my 02 plate "C" Class
with only 45,000 miles on the clock. The first was renewed Aug 05 on
the off side rear (R/H/R) and the second today on the near side rear
(L/H/R).

Also in that time the spring price has gone from £27.00 to £40.00,
whilst the total labour bill has gone up just £6.00.