Morrisons review: Lost gift card

On 16 August I came home to find a £100 fine for overstaying my parking at Morrisons in Totnes. I am a pensioner and this really scared and worried me so I paid the reduced amount of £60, which I could ill afford. I then saw on Social Media that the store was cancelling parking fines, so on the 17th, I went to speak to someone about it. I appreciate that it was a difficult situation, but I spend a lot of money in that store, so I asked the manager if they would be willing to do anything about it. He kindly gave me a gift card for £60, which I now cannot find. I was interrogated by a store manager, asking his name, what he looked like and told it was not protocol to do this. And I would have to wait until the managers came back off holiday. I have been back in again today and I have been told that there is absolutely no record of me having been given this gift card, which I find hard to believe and that there is nothing they can do to find out if it has been used or not. I have tried to call you several times (up to now I must have spent almost three hours trying to resolve this.) Please help. Thank-you, Jan Friend