I emailed viagogo (a rather stroppy email) and this was their response
We apologise if you have experienced issues in linking your Manchester City season ticket to the viagogo marketplace. Unfortunately it is not possible to link a season ticket out of season, but if you try again August 6th 2012, you should be able to process this.
Kim
We apologise if you have experienced issues in linking your Manchester City season ticket to the viagogo marketplace. Unfortunately it is not possible to link a season ticket out of season, but if you try again August 6th 2012, you should be able to process this.
Kim