Whenever I can’t purchase theatre tickets directly from the theatre, as it’s in London, I use Theatre Tickets Direct, which is a great alternative and usually the prices are roughly the same.
A few example of tickets I have purchased and theatre shows I have attended through Theatre Tickets Direct are The Lion King and We Will Rock You.
I have never had to return, or attempt to return, any of my tickets. Nor have I ever had an issue with my tickets where I have had to contact the customer support.
Overall, I rate this company as excellent and highly recommend it.