They must have changed their attitude: a few years ago (pre-Zurich merger), Eagle Star was renowned for it's fussiness where modifications were concerned. Their proposal forms used to list "stripes and decals" as modifications which they would not accept!! Make sure you've got something in writing accepting your mods. However, if you did the business over the phone and there's no proposal form to refer back to, then the insurer will have to have taped the conversation if they try to rely on what you told them at a later date.