Hey there… the offers I know for Riverbelle are:
1. Buy 100 get 100 – homepage offer
2. Buy 50 Get 200 (250 = 111 spins on Kingcashalot) – alternative offer
The 75 free sounds they’ve seen an old ad for the Right Royal Bonus which ran back when the .co.uk site had a different offer to the .com – the offer was £75 match offer every month for one year.
This offer is no longer valid.
As for the installation I did some digging and it appearsa MGS did a MUP upgrade which may have messed with installations for a short time – we’ve cheked with them (and tested independantly) and all is working fine now 
Cheers,
Shane