They can be so frustrating which is why I usually use cloth! I have put flannel backed vinyl tablecloths in the dryer on low heat for 10 min. I have also ironed them in reverse on a perm. press setting under a sheet. Another alternative is draping them over a clothesline in the sun for an hour or so if the season works in your favor. :>)
Oh, my first comment! Thank you for your answer. I'm afraid it would melt in the dryer or under my iron. I think I will try to see if the sun will works, great idea!. The wrinkles are VERY stubborn! Thank you!