Well, it is now Friday and I've just phoned JBS again.
Still no sign of the brackets, but "they will phone me if they turn up!"
******** **** ***! I phoned JBS up last Saturday and was told that they would order it Monday and it would be "next day delivery" through UPS. Now I'm being told on Friday
that the part is coming from abroad and may take "some time" to arrive.
I can understand that JBS are at the fate of the post, but they could have been up front about it from the start

so I could have had time to look for an alternative

Looks like I will not be coming to the Prosport RR day tomorrow unless there is a minor miracle in the next 6 hours and it also looks like I may even be on the bus on Monday to get to work for the first time in XX years!

At this point I'm even thinking about going to get the bracket welded by a repairer and charge JBS for it!
Not happy at the moment, I've been on holiday all week and not been able to use the car at all!