how to contact you??!

I have a problem with sandals that I got from Markhams recently. HOW to contact the call centre please... called last week, 'invalid selection' no matter which option you press. Emailed last week, no response. Called again today, 'invalid selection' despite trying all the number options. <br> <br> Please advise how to get through to the call centre or someone competent who can assist with the problem sandals that I got. Thank you