Specsavers wonderpark

2013 we went for spectacles and they had these buy one get the other pair free. and the medical aid paid partly and the was a R3000 + left to pay and they wanted it cash on collection we informed them we cannot pay that much at once and they kept quiet about it and they did not give us both the spectacles' and now we receive drs attorneys email saying we owe them R5000+ on the account.1 we did not collect the glasses as we could not pay and they were supposed to be free yet we had to pay a lump sum amount on them. 2 the fact that we receive an email after a year on the matter without giving us a chance to pay for the glasses on terms seems to be not fair.