No care at Kelloggs 'Customer Care'

On 18 August I opened a packet of Kellogg’s Granola cereal, only to find this time, that cheap ‘ol raisons where replaced by what should have been cranberries - as per pack ingredients. On 22 August they collected my 3/4 full pack for ‘investigation’. A month later, I still don’t have my replacement voucher, even though I’ve emailed them 3 times (to which they’ve never rep****) , and phoned them twice to follow up. It’s been nearly a week now and I’m still waiting for them to let me know the tracking number so they can trace it at the post office. ….I’m starting to wonder if they have posted anything at all!