Вставить вместо точек предлогиThe guarantee period which the company offered

Воткнуть вместо точек предлогиThe guarantee period which the company offered their com- puters was 12 months the date putting them operation and 15 months the date delivery. The Buyer found it rather short and wanted it to be extended two and four months respectively. But the company agreed to extend it only 13 and 17 months.As the Seller was responsible the defects which were found the equipment, they had to correct them their expense.