Sufism----....
Walaikum asalaam warahmatulahi wabarakatuh Ukhtee,
I pray you are in the best of Imaan and health.Ameen.
May Allah keep us steadfast upon the straight path until the Day of Judgement after guiding us.Ameen.
SubhanAllah the importance of the question cannot be stressed enough, since soo many people fall into this trap of sufism( I did too, and Alhamdulilahi Rabb il-Alameen, Allah saved me from it),
The first question we need to ask ourselves is, was this the way of our Beloved Prophet Peace and blessings be upon him?
Secondly, If people claim it was, then what is their AUTHENTIC proof?
(Im not talking fabricated or weak hadith- I mean 100% authentic hadeeth, the sufi attribute HUNDREDS of fabrications to the Prophet pbuh!!)
The fact of the matter is that, SubhanAllah there is no proof, the suffiyyah
cannot bring forth authentic evidence to back their statements, except the whims and desires of their sheikhs. Na-oodhubillah, we seek refuge in Allah from this!
What the prophet pbuh brought us , we accept, and what he ordered us to do, we do..and lets not forget the beautiful hadith of the Prophet pbuh:
The Prophet (peace and blessings of Allaah be upon him) said: “Whoever innovates something in this matter of ours [i.e., Islam] that is not a part of it, will have it rejected.” (Bukhari & Muslim)
and who ever attributes that to the prophet pbuh, which he did not say,
should take their place in the hell fire-
Please view the following links, with
full information WITH evidence, Alhamdulilah
http://www.islamqa.com/index.php?ref=4983&ln=eng&txt=sufi
http://www.islamqa.com/index.php?ref=6745&ln=eng&txt=sufi
http://www.islamqa.com/index.php?ref=5638&ln=eng&txt=sufi
I hope this helps clarify things inshaAllah..
InshaAllah sister, if you advise them with sincerity, give them evidence from authentic narrations and inform them that this is a misguidance and if we truly love Allah we will follow His Messenger's pbuh path, and the only way to be on the right path, is first and foremost by asking Guidance from Allah swt, and learning and knowing the Quran and living the sunnah of Muhammed pbuh according to saheeh(authentic narrations) bi'idhnillah..
If we tread a step in the wrong direction and take from that which the prophet pbuh didnt teach us and add to the religion, then surely we can be 100% certain that we have strayed from the way of the Final Messenger pbuh.
(please forgive me for being quite passionate, its just that my family are sufiyah and so I have to deal with this quite frequently )

Your sister in Islam.
also refer to nahr.wordpress.com an excerpt from the Book The Devils Deception of sufism by Ibn Jawzi-Rahimahullah.