Shocking Customer Service at Under Armour

I bought a pair of trainers online; their sizing is slightly different so the shoes were too small. I emailed them immediately and requested an exchange for a bigger size. I was advised a customer consultant would contact me within 24 hours - that was 5 days ago now!!! I am horrified at the level of customer service. They are unreachable telephonically. I now sit with expensive trainers that are too small.