LEIRSUND slatted bed base too wide

Yesterday my bed frame (manufacturer: Rauch; 140cm wide) was assembled. Afterwards, I personally put together the slatted frame Leirsund (two-piece, 2x 70x200cm). In the end, I unfortunately had to find out that the slatted frame is 1 to 2 cm too wide for the bed frame. However, my mattress from Ikea (Morgedal, also 140cm wide) strangely fits exactly into the bed frame. Ergo, only the slatted frame can have the wrong dimensions, right? What am I supposed to do? I can't afford another trip to the nearest Ikea. And now I finally want to sleep in my proper bed after 10 weeks of delivery time.

As far as I know, 70 cm wide slatted frames from IKEA are 70 cm wide, but other manufacturers only, for example, 69 cm. That’s also why "Fremdroste" fall through IKEA beds. You should google for reviews to see if that’s true.