Bad service with outsurance

My home was damaged in the storm that occurred about a month ago. I phoned outsurance and they sent their contractors out to assess the damages. Whilst their contractors were assessing the damages they brought to my attention that there was structural damages to my house.anyway the response from outsurance was very bad . So I got reputable contractors to come over and assess the structural damages and give quotes for the repairs. The structural engineers quoted in the region of between eighty to ninety thousand. I was told that underpinning was to be done. The house was too also be plastered and painted after the repairs. the cemented ground had to also be sorted out after the repairs were completed. There was quite extensive work to be done on the house so that is what they quoted for. After numerous calls to outsurance I was eventually told that their assessor that they sent out said that the estimated repairs would only cost about twenty nine thousand. I would like to know how can their assessor make that decision after I got quotes from three reputable contractors that say the cost of the repairs would be in the region of eighty to ninety thousand. I am really upset about this.. I have taken the offer they have given me because it's already been over a month and I'm not prepared to go on any further with this claim. I will definitely be cancelling my insurance with them and I will also be advising all my family and friends to do the same. I will also be warning everyone on all available media networks. Outsurance definitely does not deliver on their promises