OP - Be careful of the use of the word "compensation." You are due "compensation" for the delay and you are due a "refund" for the ticket.

You have also repeated what you were "offered." That is what you are correctly due as compensation.

However, to repeat the advice above, you will need to make a request for a refund of the ticket. That will need to be made to MT as a carrier.

In your request, ask that the refund be processed to your original form of payment within 7 business days and on the 8th day file a credit card chargeback.

Note that the passage of time hurts you here. Card issuers are only required to honor chargebacks for 60 days after the service was to have been rendered and that time has passed. Most US issuers allow a good while longer as a matter of customer service.