So my 'D'P has just asked me if we can rearrange our anniversary meal so he can go to his mate's stag do instead! 
Paint Balling during the day and a meal/piss up in the evening.
After much deliberation with a friend, I have decided upon the following punishment: He pays for my daytime entertainment- shopping, spa day, lunch with friend. Also evening entertainment- dinner out with friend with as much wine as we can glug down. As well as the anniversary cancellation fee of at least £100 for a new dress. Reasonable or should I just LTB??? 
In reality, we will just reschedule the meal for the Friday night and this works in my favour anyway as I didn't actually want to go to his mate's wedding 