The high is 53, but your above the low of 39. Nobody will agree to send an engineer because you're below the clean high estimates.
You'll only get an engineer sent out with the ISP giving the usual "if the engineer finds nothing wrong you can pay the £130 OpenReach charge". By all means go ahead and chance it if you think the risk of £130 charge is worth it. Your line is well within the estimates though.
You never answered if you had a self install or paid for an engineer install, where they setup the homehub and connected it to your pc etc.
BT go with the clean/low figures if you had a managed install. They go with the impacted/low figures if it was a self install. Your above both for download though. No ISP gives a guaranteed upload speed. If there's no fault you'll almost certainly be charged for an engineer visit.