air suspension problem

got my local garage to put two new tyres on the front today and the the disco sat down at the back about 10 mins later with much revving and it was up,but the ride is much much stiffer now,suggesting too much pressure? like to know whats the problem..and how it can be fixed....yep im a newby to the site.this is the first issue ive had with my disco..

are there any lights on the dash ? the ride height may be on the off road setting . if the light is on then press it once and then press it again.even if the light isnt on still try it ive fixed one this way already