MTE Xpress: overnight courier delivery took almost a week

We sent an important frozen scientific sample using overnight express (Thursday to Friday). It did not arrive on Friday, and we were informed after hours (after waiting the whole day) that their delivery vehicle had broken down, and that "delivery will be prioritized on Monday". Again, they kept us waiting the whole day. It eventually arrived on Tuesday, completely defrosted. The tracking website still shows that it's "out for delivery", so not even that works. This company does not respond to emails or feedback on their website, and I never got them to answer their phone. We have heard that others had similar problems, so MTE Xpress is best avoided. Postnet2postnet would have been faster and cheaper.