Strimmer problems

I was attempting to finish off some strimming today (I didn't do the bulk of the hard work, mine was just the 'last bit').
The strimmer that I bought some five years ago has always been a source of trouble, the line cartridge, of which this is the image, is the weakest link in the system and has a habit of cracking and rendering the machine useless. I have tried genuine Gardena parts and 'clone' parts (from Amazon) and they all give the same rubblsh results.
In frustration I found myself looking at online reviews of big boy's petrol brush cutters, then remembered that I did the same last year and decided I didn't use them enough to warrant the price ... so I just ordered another of these rubbish cartridges from Amazon in the hope that it lasts long enough to do at least one decent job.
Going to open a bottle of chilled white wine now!