How can I replace the glass ceramic hob on Smeg SUK62CBL8 Electric Cooker?

My glass/ceramic hob has cracked and the cracks have grown with time. I've only had the cooker for three months! The cracks have now formed chips in some places. The cooker is still being used. Smeg say they won't cover the cost of replacing it under the one year manufacturer's warrantee , even though the crack started to form on it's own and has grown with use. So I need to replace the glass hob and was wondering would it be easy to replace it myself or would I need to call in an engineer?