take a lot is a *******

I bought a 1.8l Sunbeam kettle from Take a lot.com. Upon receiving the item it was not 1.8L as advertised but a 1.7L, but that was still acceptable. The kettle has a guarantee of 12 months, but when it stopped working after 5 months i arranged to have it replaced with another kettle or a kettle with similar value, but instead take a lot send me a R200 voucher that i can only use if i buy for R400 or more. I used a voucher with my initial payment, but I also paid 75% of the order value in cash. so how is this fair. They do not want to return my broken kettle. Faizul **********