Stenaline refusing Tesco vouchers.

I live in N.I and wanted to take my children to Blackpool for a summer holiday.I hadsaved Tesco clubcard points and they could be cashed in for Stena vouchers.As Stena had stopped their Belfast-Liverpool sailing TEMPORARILY,I rang them first before cashing in the vouchers.The call centre rep assured me that a new route would be offered for which I could use the vouchers.On his advice I cashed the points in and it totalled £220 in vouchers.I also had a 30% off voucher for Stena(given to me for a previous cancelled sailing).I then booked accomodation on special offer in a holiday camp near Blackpool. Sure enough Stena then advertised the new Belfast-Liverpool route soon after.It stated on the website "Stena has now aquired the new route from Belfast - Liverpool.Itmust be booked throught he DFDS website until it is cleared by the sea authorities.Click on the link below to book"I did this and then rang the number to book and was then told that both vouchers were useless and could not be used as the route did not yet belong to Stenaline?????? My only options are to take the Belfast to Scotland ferry,followed by a 5hr drive to Blackpool (with 5 children,3 under 3,I dont think so!!) or use the Dublin to Liverpool route which means extra overnight accomodation in Dublin on the way there and the way back.I only booked this holiday as the holiday park was half price and my ferry was meant to cost no more than £50.I cant afford extra overnight stays!. I have sent an E-mail of complaint but have been sent back a "standard apology" e-mail .I have written again stating that it doesn`t solve the problem but have heard nothing.Its a disgrace and I wondered if anyone else had any problems??