Tbh Dave, I have no idea, this is what was told to the chap who had to do the job twice.
It was a trade unbranded item that was going under the OEM-Q banner, They were obtained from one of their biggest suppliers.
They have been removed from sale due to the amount of complaints / failures.
The replacements come with a 2 year warranty and the quality difference is very noticeable.
I guess we are being sold cheap trash instead of paying good money for an item thats made properly and also made to last, what we want is a manufacturer that puts his money where his mouth is.
We are not alone from what I've been reading tho, Ford and Vauxhall owners are also suffering from failing slaves, not sure tho whether that is original or replacement parts.