Unsatisfied with after sales service and guarantee

First I was so impressed with there service, ordered and paid for 2 Wendy houses to be erected on my property, this all went smoothly. Now 5 months later 2/3 panels close to the roof pitch has 5 cracks, there guarantee stated : 12 months guarantee parts & services, no questions asked. I have been told to contact the installer direct to obtain a quote for repairs. I then stated but this should fall under the guarantee, now for 2 days I keep getting the response from them stating they will speak to the installer, which is only available in the mornings, but yet no repairs set? So just be aware there after service is not as stated on there website or documents.