Unfortunately I too am in the same boat, having switched in early November and had no luck with gaining any reply from any contact I've tried to make, having heard nothing since the initial confirmation e-mail which stated I'd hear within 6 weeks
Just as FYI, there a lot of people complaining on the MSE Forum about this £50 vouchers not being made available. Link .........
Just as FYI for those still chasing the elusive £50 voucher, I emailed NOW for the umpteenth time on 4/2/19 using the following email addr ......
uk-nowtv at awin . com
(I've put blanks inbetween cos can't provide it in its actual form)
Today (7/Feb) I've finally got the e-voucher for £50.
Thank you Juliedave89 for the steer.