'Only Mercedes dealers are allowed Star diagnostics, which costs ( said to me in a slow voice for emphasis) thousands upon thousands of pounds'
Funny (not) how the cost of diagnostic equipment and code scanning charges are in line with the vehicle's RRP.
Since being stung with £50 bill to scan my A2 I bought a £10 cable and free software to read my fault codes. On other cars I've bought self contained hand-held units that cost ~£20 to read codes.