Quite a while back when Tescos started their big out of town superstores I sub contracted to clean the windows for 2 stores 6 mornings a week.  
It paid well
I did a good job in return
After 10 years a new cleaning contractor moved in and took the whole cleaning deal.
I was handed a letter of 2 lines telling me the date my services would no longer be needed and that was it!
A week after I finished the new cleaning co. offered me the w/c for 20% of what I was getting.  I was feeling so demoralised I took it!  Shortly after I quit.  I thought why should I let them walk over me.
The area manager for Tesco at that time told me how they operated (I cleaned his house windows for a few years).
They simply take the cheapest, if another co. looks like they are offering what Tesco wants then they tell them the lowst they'll pay, that is it.
I don't know if that is how they still operate, probably, but I would never work for them again!
Unless they begged me of course 

ps.  Sorry you lost them Marcus, I know how it feels.  I still hate shopping at Tesco because of what happened to me and it was years ago