Within which period can an MPU be arranged?

We have lawyers here at “board”!? The following problem: in 2002 and 2004 I was tested positively for alcohol at the tax (0.9 / 0.6). Both offenses at that time were more than two years apart and are a total of three years back. Our city is now referring specifically to these two offenses and demands an MPU … is that even permissible after this period? Even if one considers the validity of the second decision, this is at least two and a half P.S. Discussions on the pros and cons of the alleged cause are not desirable here.