Exactly the same happened to me too, also running London Marathon and held a quiz back in November, I sent emails/forms off to Leicester in September.
I also explained I was a season ticket holder etc and any prize I could collect from them no problem if they didn’t want to send anything out, I’d be happy to collect. Same as you I received the two tickets from Coventry city, no problems at all from them… then back to Leicester, they replied with something along the lines of
‘My request has been unsuccessful, but please do try again next month (bearing in mind they replied in November, the quiz was November, so I ain’t ‘trying’ next month) we offer 4 tickets for a stadium tour’. A proper ‘look at what you could’ve won’ 😂