Help cancelled vs103 16th Nov. Was prem economy what now????

So wasjust logging on to check my Tesco points added. Saw something funny on my future flight. First thought one missing then realised one had been changed . Booked flight in April LHR to BNA via Atlanta on 16/11/17 coming back 20/11/17 same route. Premium economy on virgin plane. Booked via delta website as being £500 cheaper than on virgin site. However the lhr to Atlanta flight vs103 has been cancelled
So now I'm left with what to do ( not spoke to delta as office closed ) spoke to lovely virgin lady who confirmed cancellation asabut couldn't rebook through them. I can't go for more days so I change the outward and return to the 17th and 21st..and see if I can change hotel booking probably at a cost ....or I fly with delta on an earlier flight to Atlanta... but Im nervous about not travelling in premium economy ...... will they offer a first class ticket ??? I'm not sure comfort plus is a suitable alternative... what experience have people had with this.......
