Most likely what's happening is the band is too tight and potentially the straps as well. The band and straps should fit snug enough not the dig in and cause redness and deep imprints but also should not slide when moving your body around.
It's possible you may be a 38/40 but also depends on how the cups fit as well. If the cups are uniform with it then simply try a bigger band size.
A little experimentation works wonders especially when doing a try-on prior to purchasing whenever possible.
Most likely what's happening is the band is too tight and potentially the straps as well. The band and straps should fit snug enough not the dig in and cause redness and deep imprints but also should not slide when moving your body around.
It's possible you may be a 38/40 but also depends on how the cups fit as well. If the cups are uniform with it then simply try a bigger band size.
A little experimentation works wonders especially when doing a try-on prior to purchasing whenever possible.