How much does it cost to fit a catflap into a glass door??

my boyfriend’s friend is a glzier and has taken the job of fitting our cat flap into our patio doors as would do it cheaper for us. however its now been over 3 weeks and it still not done and the price has risen from apprx £100 – £110 to £170 apparently its because the glass is thicker than usual and they have had to call in specialists, im just wondering if it would of been just as expensive if we’d called in professionals but could of had it done 2 weeks ago! can anyone help??