To not use Christmas Present

[Unintentionallycausingoffence]

My BIL and his family bought two vouchers with no expiry date for a soft play, for DS. We took DS before and as great as it was we had serious concerns regarding safety and security, DS has ASC and no awareness of danger. We haven’t used the vouchers yet but I thanked them and said we would use them at some point. It was DS birthday recently and we’ve had nothing from them, we have spoken to PIL and they haven’t mentioned any personal problems they may be preoccupied with and knowing them they would do. AIBU not using the voucher yet?

What's your complaint? That BIL/PIL haven't bought your son a birthday gift for this year?

Maybe as you told them you would use last year's gift 'at some point', still haven't, and won't be, they think you're both ungrateful and aren't bothering. Or maybe they forgot.

I need to explain. to them that why we are greatful but why we can’t use them yet

So do they know you haven't used the vouchers and you think they're sulking or something?

Why is this your problem to sort and not DHs?

Why can't he just be honest with them?

Of course you're not unreasonable to not use a gift you don't think is suitable. But I'm not sure what the point of the rest of your post was really.